1. Field of the Invention
This invention relates generally to ventilating apparatus, and has particular reference to air diffuser devices through which supply air for heating, cooling, ventilating or other purposes, is delivered into rooms or other enclosures.
2. Description of the Prior Art
Conditioned air, comprising either heated, cooled, dehumidified, humidified, or mixtures thereof is distributed into enclosed spaces within a building by means of appropriate ducts leading into appropriate ceiling, wall, or floor outlets. Numerous types of diffusers are known, some provided with louvers that may be individually adjustable, for attempting to provide effective distribution of the conditioned air according to the particular conditions prevalent in the enclosed spaces.
A particular disadvantage of the types of air diffusers heretofore available is that they are generally incapable of providing uniform distribution of conditioned air through the enclosed space, without creating drafts and uneven distribution for the conditioned air. Particularly with respect to cooled conditioned air, uncomfortable drafts of cold air are prevalent in some areas of the enclosed space, while other areas remain uncomfortably warm.
One approach to remedying this problem has been air diffusers which are said to promote mixing of the conditioned air with the ambient air within the room being cooled. Such diffusers, typically, will separate the flow of cooled air into a plurality of separate jets or streams. Such separate jets or streams are achieved by a variety of flow control devices, including deflectors, baffles, and other flow deflecting structures such as channels or the like. A common characteristic of such jets or streams is that they are substantially linear in nature.
One such device is shown in U.S. Pat. No. 2,825,274, "Air Outlet Device For Ventilating Apparatus". This patent discloses a device which is disposed transversely across the path of flow of conditioned air and which divides the supply air into separate laterally spaced apart streams. The '274 patent further states "As the supply air streams flow into the enclosure, they expand and diffuse and create more or less turbulence with the result that there occurs a more or less thorough mixing of the entrained enclosure air with the supply air in the immediate vicinity of the apparatus." Turbulent flow is not the most effective means of providing mixing.
U.S. Pat. No. 4,080,882, "Air Diffuser For Ceiling Air Outlet", discloses an air diffuser including among other things a plurality of V-shaped exit openings which compress and accelerate supply air which is being directed to the conditioned space. Another patent representative of the prior art is U.S. Pat. No. 4,679,495, "Air Diffuser". The '495 patent discloses a diffuser which has a plurality of nozzles separating the flow of air from the outlet to the ambient into a plurality of diverging air jet streams, with the result that air flowing from the outlet is "diffused and substantially uniformly distributed throughout an enclosure".
As pointed out above, the jets, or streams of supply air delivered by each of the above-noted prior art patents are separate, linear, streams of air which have a minimal effect on promoting mixing, either with one another or with ambient room air downstream from the diffuser outlets.
Another drawback of prior art air outlets for ventilation apparatus is found in devices where the air outlet is located adjacent the exposed surface of a ceiling or wall and which acts to effect more or less lateral deflection of the delivered air across the surrounding ceiling or wall area. The air delivered from such a device commonly picks up dust particles from the air contained in the room or other enclosure into which it is delivered. The flow of air from the air outlet device across the surrounding ceiling or wall area usually produces, with time, on this surrounding area, an unsightly deposit of dust, or smudge commonly referred to as a ceiling stain. Ceiling stains are generally most pronounced adjacent to the air outlet device and gradually diminish outwardly therefrom. The primary reason that the ceiling stains are most pronounced in the region surrounding the air outlets is that flow separation and recirculation results in a region of stagnation downstream from the air outlets. The stagnation zone is a direct result of the substantially linear nature of the flow in this region produced by such air outlet devices.